Electrochemical processing generally, and anodizing in particular is characteristically a batch processing technique wherein a workpiece or array of workpieces are lowered into a tank for one processing step, raised from that tank and then lowered into another tank for a subsequent processing step. Such batch processing techniques are typically large, expensive and hard to control.
U.S. Pat. No. 2,111,377 discloses such a batch processing anodizing tank where workpieces are suspended in an electrolyte solution within the tank and having an air circulating pump for agitating the solution as well as an exhaust fan for removal of noxious fumes. Another batch processing tank is shown in U.S. Pat. No. 3,971,710 wherein the electrolyte solution is recirculated between the tank and a second constant temperature reservoir.
In U.S. Pat. No. 4,081,347 illustrates another batch processing technique for electroplating wherein a partition arrangement within the tank maintains the separation of potentially explosive gases evolved at the anode and cathode, respectively. The electrolyte is subsequently removed from the tank, degassed, and returned to the tank in two separate recirculating paths to maintain that gas separation.